Page:Insects - Their Ways and Means of Living.djvu/342



the species as a whole. Independence entails responsibil- ities. A creature that leaves the beaten paths of its an- cestors must learn to take care ofitse]fin a new way. And

Flc. 15OE. The head of a tent caterpillar A, facial view. B, under surface. C, side view. .dnt, antenna; Clp, clypeus; For, opening of back of head into body; ttphy, hypopharynx; Lk, labium; Lin, labrum; 3Id, mandible; Mx, maxilla; O, eyes; Spt, spinneret

this the caterpillar has learned to do preeminently well, as it bas come up the long road of evolution, till now it possesses both instincts and physical organs that make it

F¢. x$3. The mandibles, or biting jaws, of the tent cater- pillar detached from the head A, front view of right mandi- ble. B, under side of the left mandible, a and p, the an- terior socket and posterior knob by which the jaw is hinged to the head; EAcl, RMd, abductor and adductor muscles that more the jaw in a transverse plane

one of the dominant forms of in- sect lire. The external organs of princi- pal interest in the caterpillar are those of the head (Fig. 152). These include the eyes, the an- tennae, the mouth, the jaws, and the silk-spinning instrument. A facial view of a caterpillar's head shows two large, hemispherical lateral areas separated by a medi- an suture above and a triangular plate (C/p) below. The walls of the lateral hemispheres give at- tachment to the muscles that move the jaws, and their size is no index of the brain-power of

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